Re: [9fans] Plan 9 from Bell Labs - Frequently Asked Questions [FAQ]

["Russ Cox" <rsc@plan9.bell-labs.com>]

> Subject: Is the cross product of two vectors a vector?
>
> No, it is not, and the fact that people treat it as one is the problem. The
> *geometric object* that is the closest thing to the c.p. is a skew tensor
> (practically the same as wedge product), which (only) in 3D has Cartesian
> components that resemble those of a vector, *except* that this pseudo-vector
> *flips* under reflection (unlike a genuine vector). Unfortunately,
> physicists have been trained to express Maxwell's laws as a relationship
> between a genuine vector (field) and a c.p., which means that that
> expression of those laws *changes* under reflection, something that
> physicists are *not* taught and which appears to have been overlooked in the
> analysis of the (nonconservation of) parity experiment.
> I had to quote Douglas Gwyn verbatim on this, because I have no *ucking clue
> what he's talking about -- Steve

☺